ANISOTROPY AND GROWTH-SEQUENCE DEPENDENCE OF ATOMIC-SCALE INTERFACE STRUCTURE IN INAS GA1-XINXSB SUPERLATTICES/

We have used cross-sectional scanning tunneling microscopy to study th e atomic-scale interface structure of InAs/Ga1-xInxSb superlattices gr own by molecular beam epitaxy. Detailed, quantitative analysis of inte rface profiles obtained from constant-current images of both (110) and (1 (1) over bar 0) cross-sectional planes of the superlattice indicat e that interfaces in the (1 (1) over bar 0) plane exhibit a higher deg ree of interface roughness than those in the (110) plane, and that the Ga1-xInxSb-on-InAs interfaces are rougher than the InAs-on-Ga1-xInxSb interfaces. The roughness data are consistent with anisotropy in inte rface structure arising from anisotropic island formation during growt h, and in addition a growth-sequence-dependent interface asymmetry res ulting from differences in interfacial bond structure between the supe rlattice layers. (C) 1997 American Institute of Physics.